Question

Thigmotropism is the movement of plant part in response to
(a)Chemical
(b)Touch
(c)Gravity
(d)Light

Answer 1

Hint: It can be in the form of opening or closing of parts of the plant such as the petals or leaves, the coiling of the plant around the surface, as well as other ways. The orienting factor is generally an extreme surface that will alter the course of the plant's development or the extension of 1 of its organs.

Complete answer:
The directed growth responses that make the plant grow in direction of or faraway from a stimulus are referred to as tropic movements. Directed growth of plants caused by light is known as phototropism. Gravitropism is the growth response of plants in direction of gravity. Growth responses in response to the touch are referred to as thigmotropism. Chemotropism is a growth response to chemicals.

Additional Information:
 Types of Thigmotropism
Differential Growth
Differential growth is where one side of the plant is signaled to grow faster than the remainder of the plant upon stimulation. Specialized epidermal cells cause this different rate of growth, and it's seen within the growth pattern of tendrils. Differential growth can occur within minutes and is typically long-lasting.
Rapid Contact Coiling
Rapid contact coiling, on the opposite hand, is a moment response. It happens quickly and doesn’t last long. An example of this is often the folding of the leaves of some plant species upon being touched. Now and again, fast contact curling happens first and is then trailed by the increasingly slow perpetual differential development.
So the correct answer is ‘Touch’.

Note: Thigmotropism is one example of tropism, which is the response of a plant to environmental stimuli by growing towards or away from them. In other words, the reaction is often positive or negative. For example, a stem can develop upwards towards the sun, and roots can become distant from an object inside the soil. Different types of tropism incorporate phototropism, which is a plant's reaction to light.